1. Field of the Invention
The present invention relates to a color management system for generating color measurements from transform-based color profiles for use in a measurement-based color management system.
2. Description of the Related Art
Typically, color management systems utilize standardized transform-based color profiles for the conversion of color image data between device-dependent and device-independent color spaces. Such transform-based color profiles are often created by a hardware manufacturer of a given color device, such as a printer or a digital camera. Typically, transform-based color profiles are designed to meet the specifications set forth by the International Color Consortium (ICC). The current specification is entitled Specification ICC. 1:2003-09, File Format for Color Profiles [Version 4.1.0], Sep. 24, 2003, and may be found at http://www.color.org/icc_specs2.html. The contents of the current specification are incorporated herein by reference.
A color transform contained in a transform-based color profile can be in the form of an n-dimensional lookup-table (LUT) or a set of tone reproduction curves (TRC) and a matrix. For instance, in the case of a CRT monitor, a set of tone reproduction curves and a matrix can be used by a CMM to convert RGB values used by the device to device-independent color space values. The device-independent color space values can then be converted to a device-dependent color space utilizing the same CMM in combination with another device's transform-based color profile.
More recently, measurement-based CMMs have been developed that use device profiles which include actual measurements of the device's color characteristics, such as XYZ measurements of color patch data from an IT8.7/2 target. Measurement-based CMMs are sometimes called “smart” CMMs for their ability to use the actual measurements to obtain increasingly refined color characteristics of the profiled device.
Unlike a typical transform-based CMM, however, measurement-based “smart” CMMs cannot directly utilize the color transforms contained within transform-based color profiles. This is because “smart” CMMs directly utilize color measurement data profiles corresponding to a color device to generate a color transform for converting image data from a device-dependent color space to a device-independent color space.
Given the widespread use of transform-based color profiles for color devices, such as ICC color profiles, it is desirable to have a method for utilizing these transform-based color profiles in combination with a measurement-based “smart” CMM.